Many medical tests are performed by examining a biological specimen, e.g., blood, pus, or urine, applied to a microscope slide. Typically, the biological specimen is “smeared” onto the slide and, then, treated with a reagent, such as a stain, to make features of the smeared biological specimen more visible. Often, the slide is then rinsed to remove excess reagent and dried for handling by laboratory personnel.
Automated slide stainers are available that automate the process of staining, rinsing, and drying smeared slides. One type of automated slide stainer is a dip and dunk slide stainer. In a dip and dunk slide stainer, one or more vessels are filled with reagents. The reagents are then applied to the slides by loading the slides into a slide carrier configured to accept up to a fixed number of slides (e.g., 40 slides) and selectively lowering the slide carrier containing the slides into the vessels, which are configured to accept the fixed number of slides.
Some of the reagents used for slide staining are very expensive and many cannot be reused, e.g., due to contamination. If the slide carrier is full (i.e., includes the fixed number of slides), then the price of the reagents is spread across a relatively large number of slides. If the slide carrier is not full, however, fewer slides are processed using the same amount of reagent. Thus, the reagents are less efficiently utilized when the slide carrier is not full, which results in a higher per slide processing cost.
There is an ever-present desire to reduce costs associated with laboratory processes such as slide-staining. Fluids such as reagents used in slide stainers contribute to the cost of slide staining processes. Accordingly, there is a need for slide staining methods and apparatus that more efficiently utilize these fluids. The present invention addresses this need among others.